We have a 2001 Daewoo Lanos 4dr and had a similar problem ever since we owned it. We had it in for service a lot of times, but the only thing that ever showed was a misfire in the cylinder. They even paid to have the heads re-machined at one point which never helped. Finally, we decided to start using 5W/30 synthetic oil on the oil changes which seemed to have worked. Prior we were concerned about driving the car too far from home, but we've driven it as much as 2 hours away. It costs a little more, but it's worth a try.
A train parked for the night but expected to move is usually referred to as "tied down".
Often cars that are parked overnight need to be recharged. It is possible that the battery has died and needs a replacement or a jump to start.
I believe you are "standing", not parked.
I have parked at Stanmore Station overnight, I think it was £1 for the whole weekend. Used tube to get into Central London whilst seeing a show. Really easy.
If your car is running when parked then it is burning gas. Cars use gasoline to run the engine.
Does the dome lights not stay on when the doors are left open?
This is not the cause, this relay is to start the and run the compressor (Basically) and it will not cause the system to lower overnight.
Leave the car parked unlocked on a large city street overnight. The radio should be gone by morning.
Yes. Some stores may have areas specifically for larger vehicles to park in so that they're not parked in the main parking lot.
If no engine light is on it could be fuel filter
Exhaust fumes may enter and that is not good.
Depends. If it is a public road, there is no restriction. If it is main road, such as 25A, police will ticket at narrow points.